Apply same logic as we use for rendering preview cached versions

of vector layers to point cloud layer renders
qgis · Jan 28, 2021 · c642169 · c642169
1 parent ab94b20
commit c642169
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Showing 5 changed files with 46 additions and 2 deletions.
diff --git a/python/core/auto_generated/qgsmaplayerrenderer.sip.in b/python/core/auto_generated/qgsmaplayerrenderer.sip.in
@@ -112,6 +112,7 @@ least partially) some data
 
 
 
+
 };
 
 /************************************************************************

diff --git a/src/core/pointcloud/qgspointcloudlayerrenderer.cpp b/src/core/pointcloud/qgspointcloudlayerrenderer.cpp
@@ -33,6 +33,7 @@
 #include "qgscircle.h"
 #include "qgsmapclippingutils.h"
 
+
 QgsPointCloudLayerRenderer::QgsPointCloudLayerRenderer( QgsPointCloudLayer *layer, QgsRenderContext &context )
   : QgsMapLayerRenderer( layer->id(), &context )
   , mLayer( layer )
@@ -60,6 +61,8 @@ QgsPointCloudLayerRenderer::QgsPointCloudLayerRenderer( QgsPointCloudLayer *laye
   mCloudExtent = mLayer->dataProvider()->polygonBounds();
 
   mClippingRegions = QgsMapClippingUtils::collectClippingRegionsForLayer( *renderContext(), layer );
+
+  mReadyToCompose = false;
 }
 
 bool QgsPointCloudLayerRenderer::render()
@@ -86,13 +89,25 @@ bool QgsPointCloudLayerRenderer::render()
     mRenderer->startRender( context );
     static_cast< QgsPointCloudExtentRenderer * >( mRenderer.get() )->renderExtent( mCloudExtent, context );
     mRenderer->stopRender( context );
+    mReadyToCompose = true;
     return true;
   }
 
   // TODO cache!?
   QgsPointCloudIndex *pc = mLayer->dataProvider()->index();
   if ( !pc || !pc->isValid() )
+  {
+    mReadyToCompose = true;
     return false;
+  }
+
+  // if the previous layer render was relatively quick (e.g. less than 3 seconds), the we show any previously
+  // cached version of the layer during rendering instead of the usual progressive updates
+  if ( mRenderTimeHint > 0 && mRenderTimeHint <= MAX_TIME_TO_USE_CACHED_PREVIEW_IMAGE )
+  {
+    mBlockRenderUpdates = true;
+    mElapsedTimer.start();
+  }
 
   mRenderer->startRender( context );
 
@@ -149,6 +164,7 @@ bool QgsPointCloudLayerRenderer::render()
   if ( ( rootErrorInMapCoordinates < 0.0 ) || ( mapUnitsPerPixel < 0.0 ) || ( maximumError < 0.0 ) )
   {
     QgsDebugMsg( QStringLiteral( "invalid screen error" ) );
+    mReadyToCompose = true;
     return false;
   }
   double rootErrorPixels = rootErrorInMapCoordinates / mapUnitsPerPixel; // in pixels
@@ -177,6 +193,14 @@ bool QgsPointCloudLayerRenderer::render()
 
     mRenderer->renderBlock( block.get(), context );
     ++nodesDrawn;
+
+    // as soon as first block is rendered, we can start showing layer updates.
+    // but if we are blocking render updates (so that a previously cached image is being shown), we wait
+    // at most e.g. 3 seconds before we start forcing progressive updates.
+    if ( !mBlockRenderUpdates || mElapsedTimer.elapsed() > MAX_TIME_TO_USE_CACHED_PREVIEW_IMAGE )
+    {
+      mReadyToCompose = true;
+    }
   }
 
   QgsDebugMsgLevel( QStringLiteral( "totals: %1 nodes | %2 points | %3ms" ).arg( nodesDrawn )
@@ -185,6 +209,7 @@ bool QgsPointCloudLayerRenderer::render()
 
   mRenderer->stopRender( context );
 
+  mReadyToCompose = true;
   return !canceled;
 }
 
@@ -195,6 +220,11 @@ bool QgsPointCloudLayerRenderer::forceRasterRender() const
   return mRenderer ? mRenderer->type() != QLatin1String( "extent" ) : false;
 }
 
+void QgsPointCloudLayerRenderer::setLayerRenderingTimeHint( int time )
+{
+  mRenderTimeHint = time;
+}
+
 QVector<IndexedPointCloudNode> QgsPointCloudLayerRenderer::traverseTree( const QgsPointCloudIndex *pc,
     const QgsRenderContext &context,
     IndexedPointCloudNode n,

diff --git a/src/core/pointcloud/qgspointcloudlayerrenderer.h b/src/core/pointcloud/qgspointcloudlayerrenderer.h
@@ -62,6 +62,7 @@ class CORE_EXPORT QgsPointCloudLayerRenderer: public QgsMapLayerRenderer
 
     bool render() override;
     bool forceRasterRender() const override;
+    void setLayerRenderingTimeHint( int time ) override;
 
   private:
     QVector<IndexedPointCloudNode> traverseTree( const QgsPointCloudIndex *pc, const QgsRenderContext &context, IndexedPointCloudNode n, double maxErrorPixels, double nodeErrorPixels );
@@ -80,6 +81,10 @@ class CORE_EXPORT QgsPointCloudLayerRenderer: public QgsMapLayerRenderer
     QgsGeometry mCloudExtent;
     QList< QgsMapClippingRegion > mClippingRegions;
 
+    int mRenderTimeHint = 0;
+    bool mBlockRenderUpdates = false;
+    QElapsedTimer mElapsedTimer;
+
 };
 
 #endif // QGSPOINTCLOUDLAYERRENDERER_H
diff --git a/src/core/qgsmaplayerrenderer.h b/src/core/qgsmaplayerrenderer.h
@@ -157,6 +157,16 @@ class CORE_EXPORT QgsMapLayerRenderer
      */
     bool mReadyToCompose = true;
 
+    /**
+     * Maximum time (in ms) to allow display of a previously cached
+     * preview image while rendering layers, before switching to
+     * a progressive rendering display.
+     *
+     * \note Not available in Python bindings
+     * \since QGIS 3.18
+     */
+    static constexpr int MAX_TIME_TO_USE_CACHED_PREVIEW_IMAGE = 3000 SIP_SKIP;
+
   private:
 
     // TODO QGIS 4.0 - make reference instead of pointer!

diff --git a/src/core/vector/qgsvectorlayerrenderer.cpp b/src/core/vector/qgsvectorlayerrenderer.cpp
@@ -44,8 +44,6 @@
 
 #include <QPicture>
 
-constexpr int MAX_TIME_TO_USE_CACHED_PREVIEW_IMAGE = 3000;
-
 QgsVectorLayerRenderer::QgsVectorLayerRenderer( QgsVectorLayer *layer, QgsRenderContext &context )
   : QgsMapLayerRenderer( layer->id(), &context )
   , mLayer( layer )